Project Summary/Abstract Suicide attempts are high-risk but low-base rate events that are associated with a range of commonly- occurring transdiagnostic risk factors. There is a need to move away from evaluating generalized vulnerabilities that are associated with suicidality, and towards achieving a better understanding of the specific sequencing of vulnerabilities under which otherwise distal risk factors cascade upon one another to contribute towards more immediate suicidal crises. Many contemporary models of suicide identify dysregulating interpersonal experiences as contributing to self-destructive urges and behaviors1, 2, 3. Research has additionally identified disturbances in arousal and self-regulatory functioning, such as chronic sleep disturbance and reduced cognitive control, as markers of suicide risk4, 5. A small but growing literature suggests an event-contingent relationship between interpersonal, arousal, and cognitive impairments and proximal escalations in suicidal ideation, though few studies have evaluated these links directly. The present study hypothesizes that disturbed sleep will impair the following day's capacity for effortful control of dysregulating interpersonal situations, leading to proximal increases in suicidal ideation. Using ecological momentary assessment (EMA), the current study incorporates self-report and physiological measures of sleep with daily smartphone assessments of suicidality and impairments across psychological and behavioral domains over a two-week period. We seek to identify the mechanisms through which sleep disturbance impairs self-regulatory and interpersonal functioning, creating the conditions for proximal development of suicidality. The sample will consist of 105 adult psychiatric patients recruited from four clinical sites representing a range of severity in clinical functioning, including a university-based counseling center, outpatient community psychotherapy clinic, outpatient psychiatry clinic, and long-term residential treatment facility. This study builds on the strengths of the research team, who have a history of evaluating social cognitive impairments as vulnerability for suicide in high-risk clinical samples. Our pilot data has shown biased perceptions of social events in EMA ratings of patients with active suicidality, elucidating proximal markers of the social ruptures that precede suicidal ideation. Additionally, our prior research has evaluated both social cognitive vulnerabilities (i.e., rejection sensitivity) and self-regulatory capacities (i.e., effortful control) as moderators of daily affective experiences and interpersonal behaviors, using EMA in nonclinical samples. This study harnesses the benefits of multimethod and mobile assessment techniques to evaluate risk factors for suicide using more precise temporal resolution to map the interactive role of self-regulation and suicidal impulses in the context of everyday life.